Neuroscientists conducted a series of cognitive tests with monkeys-monkeys with a damaged hippocampus: despite the conventional wisdom, violations of the hippocampus did not affect memory and other cognitive abilities of animals. The authors of an article published in the journal Science Advances, I believe that it is necessary to reassess the role of other brain structures in cognitive functions that are usually associated with the hippocampus.
The hippocampus has long considered a structure required for memory formation of different types, as damage to the hippocampus is associated with anterograde amnesia (a loss of memory of recent events). However, more scientific data questioning the critical role of the hippocampus in memorizing and storage of information and to think about the importance of other brain areas in these processes.
The most famous patient, studying of which scientists have made many conclusions about the role of the hippocampus, was Henry Malison, or H. M. Struggling with epilepsy, doctors removed him both halves of the hippocampus, and since he could not remember new events. H. M. died in 2008, his brain was removed and studied — as a result, scientists confirmedthat, in addition to the hippocampus, the patient had extensive damage and other zones: the temporal lobe of the brain, the frontal cortex, the mastoid bodies and thalamus, as well as the integrity of white matter. In addition, it was found that H. M. has preserved a greater percentage of the hippocampus than was considered during his lifetime.
Other patients with amnesia also found collateral damage to the mastoid bodies and anterior thalamus, while previously violations associated only with dysfunction of the hippocampus. The loss of substance outside of the hippocampus in these cases it is better correlated with memory disorders.
In General most of the information about the functions of the hippocampus obtained from studies on rodents, and work with people find a correlation and not causation. In this regard, it is surprising the scarcity and inconsistency of the work on primates: in monkeys, so far explored mainly allocentrics episodic memory (as opposed to egocentric based on external benchmarks), and in studies of hippocampal powerideal often appeared affected and other brain areas.
A group of scientists from the United States under the leadership of Benjamin Basile (Basile Benjamin) from Emory University decided to close the gap in experimental data on the role of the hippocampus in memory formation in primates. Five macaques-the rhesus monkey in the hippocampus injected excitotoxin — it caused extensive damage to the structure, but kept the integrity of the conductive path of the white matter. Before surgery and after, and with five healthy monkeys performed a series of tests on memory and thinking. Animals are operated on a touch screen: they were taught to classify or build order pictures on the basis of certain regularities, and then tested how subjects learned these regularities.